Given that Translate uses Language::getLanguageNames(), I think this should be a broader feature request, asking to allow manipulation of Language::getLanguageNames(). Translate uses Language::getLanguageNames() and this would solve your issue MediaWiki-wide.

Does it need to be per group?

(In reply to comment #2)

Does it need to be per group?

Especially in aggregate groups that may lead to issues. I think I might want to have this set to WONTFIX, or assign it a very low priority...

I'd like to have more info on this. Since the correct language is selected by default in the normal use case, it doesn't seem to be a problem to list all languages there.

Correct my if I'm wrong, Robert, but this is about supporting a defined set of languages/codes, instead of "whatever MediaWiki support" when using Translate, correct? I then tried to get the scope of this feature request broadened to allow defining a set of language codes that MediaWiki would allow as locales in comment 1.

robert wrote:

The context of the original request is that we were only localising in to a very small number of languages, and so wanted the list to only display those we were (for convenience and aesthetic reasons).

FWIW I am no longer involved in that project, so the outcome of this bug isn't much of a concern to me, though I think it would be useful for some instances outside of translatewiki.net.

We have priority/restricted language features. Will accept patches but not a priority for us.